Population viability analysis of woolly monkeys in western Amazonia

Abstract

Colombian woolly monkeys (Lagothrix lagothricha lugens) are a critically endangered subspecies with little or no demographic information available to quantitatively assess the impact of various threats (e.g. poaching, disease, and habitat loss) on its population. We use 15 years of published monitoring data on a population of Colombian woolly monkeys in Tinigua National Park, collected between 1987 and 2002, to characterize basic vital rates and population parameters. Our approach uses stage-structured models to estimate population parameters coupled with projections using a state-space model. This coupled approach allows us to take into account population stochasticity and observational uncertainty, the facilitation of incorporation of prior information on population dynamics and on monitoring and simulation processes. Using projection intervals of a year, we found that adult female survival contributes the most to population growth (γ), which is barely increasing for this population (1.009). Hunting of adult females affects population dynamics disproportionately and can lead quickly to population collapse if more than 2 % of females are hunted per year. We also showed that face-whitened disease has a small effect on population growth rate (∼1 %) but may have a potentially large effect over the long term.